Technical Field
The present disclosure is directed to multichannel transducer devices and, more particularly, multichannel transducer devices and methods of operation thereof that map a low gain signal onto a high gain signal to form a blended signal and that smoothly transition to the blended signal when the high gain signal saturates.
Description of the Related Art
Devices are becoming more sensitive and more precise about detecting or sensing the environment around them. In order to detect a high dynamic range of signals, these devices include multiple acquisition channels with different sensitivities (e.g., multiple sensors with different sensitivities). The range of a single acquisition channel is too limited to detect the full range of detectable signals.
Devices that include more than one acquisition channel, such as a low sensitivity acquisition channel and a high sensitivity acquisition channel, are becoming more common in everyday electronics. For example, cellular phones, game controllers, and other mobile devices incorporate microphones, gyroscopes, or other transducer-based devices (e.g., optical devices) that are configured to sense a wide range of incoming signals.
As an example, in order to sense this wide range of signals, a microphone may include multiple membranes or multiple microphones in a single package, where one has a low sensitivity and another has a high sensitivity. As another example, a single sensor (e.g., microphone membrane) with a relatively large sensitivity range may be provided as input to two different acquisition chains that respectively implement different amplification factors. Such may result in a device that appears to have two or more acquisition channels of different sensitivity.
Generally, the low sensitivity acquisition channel enables detection of strong portions of an environmental signal (high amplitude), but does not handle weak portions of the signal (low amplitude) well. The high sensitivity acquisition channel enables detection of the weak portions of the signal (low amplitude), but does not handle the strong portions of the signal well.
In current devices with multiple acquisition channels, a control circuit simultaneously acquires the output signals of different sensitivities from the two channels and adapts to the signal strength by directly switching between the high sensitivity and low sensitivity signals.
However, such switching creates unwanted discontinuities in the output signal. In particular, there may be a delay when switching between the high and low sensitivity signals. As another example, a discrepancy between noise floors respectively associated with the high and low sensitivity signals may be discernable when switching occurs (e.g., by a listener of an output signal switched between channels of a dual-channel microphone device). In addition, control circuits for the gain are often arranged away from the sensor in the chain of signal processing and fail to compensate for inherent limitations of the sensor.